The present invention relates to an oscillating circuit comprised of integrated circuitry which operates at a voltage lower than the built-in voltage of the PN junctions forming the integrated circuitry.
Recently, quartz crystal timepieces have been in popular use owing to their high precision. Particularly, X-cut quartz crystal vibrators having secondary temperature coefficients whose top temperature is near room temperature are in general use because of their low natural frequency of around 32 KHz and their capability of being small sized. However, it is difficult for this type of quartz crystal vibrator to achieve the desired time accuracy such as error of several seconds per a year, and thereby an AT cut quartz crystals having tertiary temperature coefficients are usually required. However, since the frequency band of the AT cut quartz crystal is more than several MHz, the power consumption of the AT cut quartz crystal of C-MOS or I.sup.2 L construction such as are conventionally used is large and consequently a battery life of more than several years for a wrist watch cannot presently be satisfied.
Accordingly, the present invention aims to provide a quartz crystal oscillating circuit which operates at a voltage lower than the built-in voltage of the circuit PN junctions.